Glomeruli are clusters of small blood vessels in the kidney that allow waste to pass from the blood and into the urine. Glomerulonephritis occurs when the glomeruli swell, damaging the kidneys and interfering with the removal of waste, electrolytes, and excess fluids. Damage to the glomeruli may cause excess blood and protein to be lost in the urine. The condition can come on suddenly or develop over time and has multiple causes.
A variety of infections can cause glomerulonephritis. For example, it may occur after a week or two recovering from strep throat or bacterial endocarditis, especially in people with heart defects. Viral infections like HIV and hepatitis can also cause it. The body produces extra antibodies when fighting infection, and they can settle in the glomeruli and cause inflammation.
Some immune diseases can also cause glomerulonephritis. Lupus is an inflammatory disease that affects many areas of the body, including the skin, joints, heart, and kidneys. A rare lung disorder called Goodpasture's syndrome can also cause lead to glomerulonephritis. IgA nephropathy specifically affects the glomeruli, causing immunoglobulin A to build up and eventually leading to the disease.
Vasculitis and scarring can also cause glomerulonephritis. Polyarteritis and granulomatosis affect the small and medium blood vessels in the body, including those in the kidneys. High blood pressure and diabetic kidney disease can cause scarring that leads to glomerulonephritis. Focal segmental glomerulosclerosis also causes scarring of the glomeruli.
Glomerulonephritis can also be inherited. These forms of the disease include Alport syndrome, which also causes vision and hearing impairment, and Charcot-Marie-Tooth neuropathy, a peripheral nervous system disease that affects muscle tone and touch sensation. Inherited glomerulonephritis is rare. In the majority of cases, it is caused by an immunologic response, though sometimes the cause is unknown.
About half of people with glomerulonephritis have no symptoms. If they do, swelling is usually the first to appear because the body is retaining fluid. Other common symptoms include blood in the urine and foamy urine, which is due to excess protein. As kidney function declines, blood pressure increases and tiredness and confusion can develop. In older people, non-specific symptoms like malaise and nausea are common.
Acute glomerulonephritis is usually a complication of a strep infection. It most commonly develops in children between two and 10 after they recover from strep throat. This form can also be caused by chickenpox, staph infections, and parasitic infections. When this happens, it is diganosed as postinfectious glomerulonephritis.
Chronic glomerulonephritis usually results from the same infections as acute. In some cases, though, acute glomerulonephritis does not resolve and becomes a long-term problem. Inherited conditions also lead to this form, but often the cause idiopathic, which means doctors cannot identify it.
Doctors evaluate for glomerulonephritis depending on the symptoms that have developed. If it is suspected, multiple tests are performed, including blood counts, renal function tests, and serum electrolytes. Urine tests may show protein or clumps of red or white blood cells called casts. A renal biopsy may determine the extent of glomerular involvement and damage.
Treatment depends on the cause. If the condition is progressing rapidly, doctors often administer immunosuppressants. There is no specific treatment for acute glomerulonephritis. If it is caused by a bacterial infection, it usually begins after the infection has resolved, which means that antibiotics are not effective. Corticosteroids may help decrease the inflammation and reduce symptoms. A diet low in sodium and protein is necessary until the kidneys recover. Diuretics can help the body excrete excess fluid, and high blood pressure is monitored and treated.
Glomerulonephritis may resolve, and the kidneys can heal, though the condition may also progress and cause more damage. Complications include chronic kidney disease, end-stage renal failure, high blood pressure, and nephrotic syndrome. The latter results from too little protein in the blood, which leads to high cholesterol and swelling around the eyes, feet, and abdomen.
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